1. Field of the invention
The present invention relates generally to a medical device for delivering fluids to a patient. Specifically, the invention relates to a small, low-cost, portable infusion device that can be used to transcutaneously deliver therapeutic fluids to a patient. The present invention also relates to systems and methods for detecting an occlusion in a fluid passageway in the infusion device that includes disposable and reusable parts.
2. Background
Conventional methods and systems for detecting an occlusion in a fluid delivery tube are based on a detection of tube's radial expansion. The expansion is caused by an elevation of an upstream pressure that is caused by a downstream occlusion. Exemplary conventional systems are disclosed in U.S. Pat. No. 4,373,525 to Kobayashi and U.S. Pat. No. 6,423,035 to Ras et al. Other conventional systems and methods for detecting an occlusion are disclosed in U.S. Pat. No. 4,369,780 to Sakai (“Sakai”), U.S. Pat. No. 6,149,394 to Allen (“Allen”), U.S. Pat. No. 6,830,558 to Flaherty et al. (“Flaherty”).
Sakai discloses a magnet sensitive element for the detection of a flexible tube expansion. Allen discloses an apparatus and a method for detecting an occlusion using a portion of tube, which has a thinner wall section. When a downstream occlusion occurs, pressure elevation causes expansion of the thinner wall section of the tube. Flaherty discloses an apparatus and a method for detecting an occlusion by means of a sensor assembly that includes a resilient diaphragm having one surface positioned against the flow path's tube and a chamber wall positioned adjacent to the second surface of the diaphragm. A first electrode is positioned in the diaphragm, a second electrode is positioned in a fixed location and an impedance meter measures impedance between electrodes. In response to fluid flow conditions occurring in the flow path's tube, the second surface of the diaphragm expands and an electrical signal is provided accordingly.
However, most conventional systems and methods do not reliably detect an undesirable occlusion in the tube. The existing occlusion detectors are not sensitive enough and fail to detect partial occlusions. Further, most conventional detectors require a long lag time before alarming the patient of the occlusion. Additionally, they are expensive to produce and bulky.
Thus, there is a need for less expensive, accurate and sensitive systems and methods for the detection of partial and/or full occlusion(s) that may occur in the fluid infusion system.